I'dd root for them being friends with benefits while they're single. Or in a lose polycule situation lol.
There's too many good shipping options for dick greyson for him to pick just one. Besides which, most of the ladies in his dating roster are super-busy super heroines, and that's before we get into dick's own heroic scheduling conflicts. It makes sense for them to have a 'whenever & whoever we can get away from the current crisis of the month is fine' romantic arrangement.
Plus you know Harley is usually down to clown. She'd love the pure chaos & ground floor access to the drama of polycule life.
If ivy insisted on exclusivity in their relationship Harley *would* respect it but also drop hints about wanting a threesome for special gift giving occasions. (Christmas, valentines, birthdays etc). Ivy being plant-pilled probably wouldn't mind Harley having occasional preapproved flings so long as she uses protection & doesn't come home with any surprise human larvae.
